In network environments that use network address translation (NAT), selecting the path (defined by a pair of transport address) over which communication is to be supported between two endpoints is important. This is because impairments, such as jitter, delay and packet drops, on a given path can greatly degrade the quality of the communication session. In the case of real-time communications (voice, video, etc.), the consequences of jitter, delay and packet drops can be devastating in terms of user perception and whether or not the call is ultimately successful.